1. Field of the Invention
The present invention relates to multi-path data, and more particularly, to a recording/reproducing apparatus recording and reproducing data with a multi-path structure and an information storage medium on which the multi-path data is recorded.
2. Description of the Related Art
A multi-path denotes a plurality of paths including language credit data and multi-angle data, through which Audio-Video (AV) data is reproduced/recorded. A digital versatile disc (DVD) is a representative of conventional information storage media on which multi-path data is recorded using an interleaving method in which the data is divided into predetermined units and the units are alternately recorded. The interleaving method enables quick reproduction of data stored on a related path when a path change is instructed by a user. Generally, the multi-path recording is performed with regard to an information storage medium which has no recording position restrictions and a multi-path data structure in which data is recorded to have different reproduction times.
FIG. 1 illustrates a data structure of a DVD with a multi-path data configuration according to the interleaving method. Referring to FIG. 1, the DVD is divided into a video management group (VMG) area 110 and a plurality of video title set (VTS) areas 120a through 120n. Information regarding management of titles and title menus is stored in the VMG area 110 and information regarding titles is recorded in the plurality of VTS areas 120a through 120n. In general, the VMG area 110 comprises two or three files and each of the VTS 120a through 120n area comprises three to twelve files.
FIG. 2 illustrates a detailed data structure of the VMG area 110 of FIG. 1. Referring to FIG. 2, the VMG area 110 includes a video management group information (VMGI) area 112 containing additional information regarding the VMG area 110, a video object subtitle (VOBS) area 114 containing video object information regarding the title menu, and a VMGI backup area 116. Each of the VMGI area 112, the VOBS area 114, and the VMGI backup area 116 exists as a file. However, the inclusion of the VOBS area 114 in the VMG area 110 is optional, so that in some cases, the VOBS area 114 may not be formed in the VMG area.
FIG. 3 illustrates a detailed data structure of the VTS area 120n of FIG. 1. Referring to FIG. 3, video title set information (VTSI) 310, VOBS 320 for a menu, which is presentation data for a menu screen, VOBS 330 for a video title set, and VTSI backup data 340 are recorded in the VTS area 120n. Recording of the VOBS 320 for menu is optional for displaying a menu screen. The VOBS 330 for a video title set is divided into a plurality of video objects (VOBs) and a plurality of cells that are recording units. Each VOB comprises a plurality of cells. In this disclosure, the basic recording unit is a recording cell.
FIG. 4 illustrates a video title linked to a plurality of program chains (PGCs) for controlling reproduction of the video title video objects according to the interleaving method. As shown in FIG. 4, when one of the plurality of PGCs is selected and reproduced after reproduction of another PGC, a command for determining the PGC to be selected and reproduced may be stored on the DVD. Controlling the sequence of reproduction is referred to as navigation. A command for determining navigation is contained in program chain information (PGCI).
FIG. 5 illustrates a data structure of the PGC according to the interleaving method. Referring to FIG. 5, the PGC is stored in a PGCI 510. The PGCI 510 contains a pre-command 512 that includes a navigation command, a post-command 516, and a plurality of programs 514a through 514n. The pre-command 512 is carried out prior to reproduction of a particular program linked to the PGC and the post-command 516 is carried out after the reproduction of the particular program linked to the PGC. Each of the programs 514a through 514n contains a plurality of reproduction cell information. Reproduction cells included in the programs 514a through 514n are linked to respective recording cells as recording units included in a VOB. Each reproduction cell, i.e., a reproduction unit, has a reproduction cell command (CC) that is carried out after reproduction thereof. Therefore, the PGCI is a hierarchical description of the PGC, which is a reproduction unit, and has an information structure that links a reproduction cell, which is the basic reproduction unit, to a recording cell that is the basic recording unit. In particular, the PGC is a link of a plurality of reproduction cells that are reproduction units. Here, the plurality of reproduction cells of a program 514 may form a path block.
FIG. 6 illustrates a structure of a path block 600 shown in FIG. 5. Referring to FIG. 6, the path block 600 is constructed such that a plurality of reproduction cells are arranged in parallel so that only one of these reproduction cells can be reproduced. The reproduction cells forming the path block 600 may have the same reproduction time or different reproduction times, and each of the reproduction cells corresponds to a specific path in the path block 600. If reproduction cells, which are reproduction units, form a path block 600, corresponding linked VOBs and recording cells, which are recording units, of a path of the path block 600, are not continuously and sequentially recorded per path, but recorded according to the interleaving method.
FIG. 7 illustrates an example of a reproduction path of presentation data. A presentation engine reproduces presentation data in response to a presentation command given from a navigation manager. A series of presentation data are recorded in consecutive logical sectors according to a sequence of reading the series of presentation data during multi-path presentation data recording. The presentation data contains multiple recording cells and the navigation manager gives the presentation command with respect to at least one recording cell. Thus, the reproduction path of the presentation data is determined by the sequence of recording cells prescribed by a PGC.
FIG. 7 illustrates multi-path reproduction of presentation data for a movie, where a recording cell from among a plurality of recording cells of the movie is reproduced according to navigation (reproduction command) data. In FIG. 7, “language credit” indicates reproduction of the movie according to a type of language. For instance, in the last scene of the movie, the type of language describing subtitle information regarding characters or producing staff is determined by the “language credit.” Otherwise, when the movie includes a scene where a character reads a newspaper, the newspaper may be determined to be a Korean newspaper or an English newspaper according to the “language credit”. Also, “director's cut” denotes a particular sequence of video objects of the movie, selected by a movie manufacturer, and “multi-angle” denotes that the movie was shot at multiple camera angles. The presentation data shown in FIG. 7 can be reproduced following multiple paths without pause. Such reproduction of data is called seamless play. Regarding angle data, typically, during reproduction of a movie, a user can change reproduction of one of angle data to another angle data. However, typically, change of a language determined by the language credit is not allowed, that is, reproduction paths according to the language credit might not be changeable.
FIG. 8 illustrates a layout of presentation data with a multi-path structure for seamless play according to the interleaving method. Referring to FIG. 8, the presentation data is recorded using the interleaving method. A presentation engine sequentially reads data from an interleaved block and reproduces the presentation data following a designated path of reproduction while skipping reproduction of undesired data. If data is reproduced following a first path 810, interleaved data, i.e., a first interleaving unit (ILVU) 811, a second ILVU 812, and a third ILVU 813, for the first path 810 is reproduced while skipping reproduction of a first ILVU 821, a second ILVU 822, and a third ILVU 823 for a second path 820. For jumping to a desired track, the presentation engine requires a track buffer that enables the presentation data to be supplied to a decoder without intermission.
Therefore, when multi-path data is divided into predetermined units and recorded using the interleaving method for multi-path reproduction, data stored on the same reproduction path is not continuously recorded in the same area. Accordingly, reproduction positions are unavoidably repeatedly changed, i.e., unnecessary jumps between cells occur, during data reading. In particular, when reproducing data from an optical storage medium or a hard disc that requires a lot of time to change reproduction positions, bit rates of compressed bit streams would be limited to compensate for the reproduction position changes on the optical or hard disc storage medium that requires additional position jumping time, so that the AV data can be reproduced without intermission).